Find the flow in Cumec through a trapezoidal channel with the side slope H: V=3:1and longitudinal slope of 1 in 3000. The depth of the flow is 1 m and the bottom width is 5m. The Chezy’s constant C is 50 Solution Discharge = Area x Velocity using chezy formula V = C sqrt(mi) i = bed slope = 1/3000 C = chezy constant = 50 area of trapezoidal section = (b+nd) x d b = 5m d = 1m n = side slope = 3:1 = 3 area = A = (5+3 x1) 1 = 8m 2 wetted perimeter = P = b+ 2d sqrt(n 2 +1) P = 5+ 2x1 sqrt(3 2 +1) P = 11.32m hydraullic mean depth = m = A/P = (8/11.32) = 0.706m now Q = AC sqrt(mi) Q = 8 x 50 x sqr(0.706 x 1/3000) Q = 6m 3 /s = 6000lit/s = 6cumes .

1. Find the flow in Cumec through a trapezoidal channel with the side slope H: V=3:1and
longitudinal slope of 1 in 3000. The depth of the flow is 1 m and the bottom width is 5m. The
Chezy’s constant C is 50
Solution
Discharge = Area x Velocity
using chezy formula
V = C sqrt(mi)
i = bed slope = 1/3000
C = chezy constant = 50
area of trapezoidal section = (b+nd) x d
b = 5m
d = 1m
n = side slope = 3:1 = 3
area = A = (5+3 x1) 1 = 8m 2
wetted perimeter = P = b+ 2d sqrt(n 2
+1)
P = 5+ 2x1 sqrt(3 2
+1)
P = 11.32m
hydraullic mean depth = m = A/P = (8/11.32) = 0.706m
now Q = AC sqrt(mi)

2. Q = 8 x 50 x sqr(0.706 x 1/3000)
Q = 6m 3
/s = 6000lit/s = 6cumes